noun
derivative work; fan work
Refers to creative works (manga, novels, illustrations, etc.) based on existing copyrighted material, typically made by fans without official permission. Often associated with dōjinshi and fanfiction culture.
See also: 同人誌
彼女は人気アニメの二次創作を描いている。
She draws derivative works based on a popular anime.
二次創作は著作権に注意が必要だ。
One must be careful about copyright with derivative works.